Combination ability of citrus forms in intergeneric and interspecific hybridization

The paper assesses an effectiveness of various citrus crossing combinations in terms of testing the ovary formation, output and quality of produced seeds for the period from 1994 till 2013. In total, 47 crossing combinations were used in order to obtain the hybrid offspring. The parent forms were cultivars of Citrus unshiu, which are the donors of yields, large-fruited, of early- or mid-season ripening, short, and characterized by the high quality of fruits. As paternal forms in order to improve the frost resistance of tangerine hybrids by breeding, there were used wild deciduous species of Poncirus trifoliata, species of C. ichangensis, C. junos juzu, Citrange, cultural species of Fortunella margarita, as well as complex hybrid 3252 of F.M. Zorin’s selection [( C. unshiu x P. trifoliata ) x C. le-iocarpa ], and hybrid 202 of our selection (Kowano Wase x F. margarita ). It is shown that the effectiveness of citrus hybridization depends on biological characteristics in parental forms. The carried out analysis of the ovary and quality of the produced seeds shows that crossing combinations of Tangelo and hybrid 3252 of F.M. Zorin’s selection [( C. unshiu x P. trifoliata ) x C. leiocarpa ] were the most effective.